upgrade junit to 5 or not?

[Anilople]

Is your feature request related to a problem? Please describe.

Does need to upgrade junit 4 to junit 5?

See #4193 if we upgrade the project's test to junit 5, some test feature like @Nested annotation can be used.

Describe the solution you'd like

• change the maven dependencies
• change the import in java code
• change the ci

Additional context

awaitility use junit 4, see https://github.com/apolloconfig/apollo/blob/master/pom.xml#L282-L285

		<dependency>
			<groupId>org.awaitility</groupId>
			<artifactId>awaitility</artifactId>
			<scope>test</scope>
		</dependency>

We need to investigate that awaitility can use junit 5 or not.

[nobodyiam]

It's generally a good idea to keep infrastructure tools like JUnit up to date. But I'm not sure how much effort would it take to migrate to JUnit 5, it would be great if someone could share some experience in this topic or we may need to do some POC to estimate the effort.